<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>

  <input type="text" value="张三" placeholder="提示文本 请输入姓名">
  <input type="password">
  <input type="checkbox" class="che" >
  <select name="" id="">
    <option value="name1">张三</option>
    <option value="name2" selected>李四</option>
    <option value="name3">勿忘勿</option>
  </select>

  <button disabled>我是按钮</button>

  <script>
    const inp = document.querySelector('input')
    // inp.type = 'password'
    inp.value = '张坚'
    inp.placeholder = '请输入张坚的身高'

    const inp2 = document.querySelector('.che')
    inp2.checked = true

    const sel = document.querySelector('select option')
    sel.selected = true
  </script>

</body>

</html>